83 lines
No EOL
2.7 KiB
Markdown
83 lines
No EOL
2.7 KiB
Markdown
🌫 18 Setembro 2023 - #ASCN
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- ## Why distributed systems?
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- Modularity, decoupling different concerns.
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- Performance.
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- Dependability
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- ## How to distribute?
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- ### 1. Monolythic system
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- Architecture: [[Monolithic system.excalidraw]]
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- Multiple services for multiple targets in the same server
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- ## 2. Distributed systems
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id:: 65120d55-6bed-47db-bd53-cc4f627c33dc
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- Main distribution concerns:
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1. Replication
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2. Partitioning
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3. Service-orientation
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- All of these address scaling out a service/application.
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- Not mutually exclusive, can be combined.
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- ### 2.1 Replication
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- Architecture: [[Replication.excalidraw]]
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- Multiple copies of the same data and functionality
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- Addresses resilience and scale-out
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- ### 2.2 Partitioning
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- Architecture: [[Partitioning.excalidraw]]
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- A server is split horizontally (Sharding).
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- Addresses scale-out.
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- Can be applied to computation, data, ...
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- ### 2.3 SOA - Service-Oriented Architecture
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- Architecture: [[SOA.excalidraw]]
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- Addresses scale-out and modularity.
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- Example: micro-services.
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- #### 2.3.1 Microservices
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- Each service implements specific functionality.
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- Services can scale independently.
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- Decomposition may be troublesome: how micro is micro?
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- Consistency.
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- Complex deployment and testing
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- ## Distributed architectures
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- ### 1. Client-server
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- Architecture: [[client-server.excalidraw]]
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- Functionality and data are in the server.
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- A stub runs embedded in the client.
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- The stub is part of the server software package
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- E.g., the Web (“protocol” is HTTP)
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- ### 2. Proxy Server
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- Architecture: [[proxy.excalidraw]]
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- Multiple servers can be used transparently.
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- The proxy is a performance and availability bottleneck.
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- E.g. MongoDB
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- ### 3. Master Server
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- Architecture: [[master.excalidraw]]
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- Scale out!
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- E.g. HDFS
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- ### 4. Server Group
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- Architecture: [[server-group.excalidraw]]
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- All servers can process requests.
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- Coordination may be necessary.
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- Resiliency!
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- E.g. ZooKeeper
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- ### 5. Bus
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- Architecture: [[bus.excalidraw]]
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- The bus routes messages.
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- Participants publish and consume messages to/from the bus.
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- Decouples producers from consumers.
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- **Flexibility!**
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- E.g. Kafka
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- ### 6. Multi-tier
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- Architecture: [[multi-tier.excalidraw]]
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- Each server acts as a client of the next tier.
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- Allows independent deployment and scaling of different functionality.
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- E.g. AS + DBMS:
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- “protocol A” == Web (e.g.)
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- “Stub B” == Database Driver!
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- “protocol B” uses SQL
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- #### 6.1 State in multi-tier
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- Persistent state is harder to replicate and shard.
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- Computation is easier to replicate and shard.
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- No state in upper tiers:
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- Web browser
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- Transient / cached state in middle tiers:
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- Application server
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- Persistent state at lower tiers:
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- Database |